> Who does it now?

France sent a warship to escort its gold from the US to France. Wasn't free, probably wasn't cheap.

Sure, but anyone holding that much wealth could expect some kind of "advanced persistent threat" working against them to either destroy all of the backups, or transfer the coins to /dev/null after extracting any passcode from the owner. The keys and anyone that knew how to use them would need a high level of physical security. The "costly militarized facilities" would still be necessary, contrary to the author's statement.